1. Field of the Invention
The present invention relates to an ultrasonic probe for sending and receiving an ultrasonic wave and a method for fabricating the probe.
2. Description of the Related Art
For example, ultrasonic diagnostic equipment has been used in medical diagnosis or industrial diagnosis, in which a lesion in the body or a crack in piping is detected by sending an ultrasonic wave to a diagnostic object such as the human body or piping and receiving a reflected wave of the ultrasonic wave. The ultrasonic diagnostic equipment comprises a main body of the equipment and an ultrasonic probe for sending and receiving the ultrasonic wave.
FIG. 14 and FIG. 15 show a configuration of a conventional ultrasonic probe of ultrasonic diagnostic equipment for medical application. As shown in FIG. 14, the ultrasonic probe has a piezoelectric transducer 201. The piezoelectric transducer 201 is formed into a rectangular, piezoelectric element by dicing a platelike piezoelectric ceramic.
An audio matching layer 203 for matching audio impedance is provided at an earth electrode 201c side of the piezoelectric transducer 201, and in turn an audio lens 205 is provided on a surface of the audio matching layer 203. A backing material 209 comprising rubber having a good sound absorption performance is jointed to a signal electrode 201b side of the piezoelectric transducer 201 through epoxy based resin 207.
On both side faces of the piezoelectric transducer 201, flexible printed circuits 211 (FPCs) are disposed such that they are opposed to each other. Each of end portions of the FPCs 211 is connected to the signal electrode 201b or earth electrode 201c of the piezoelectric transducer 201 through a soldering material.
As shown in FIG. 15, the FPCs 211 are bended at approximately 90 degrees in the vicinity of the connected portion to the piezoelectric transducer 201, and a rear anchor portions of the FPCs are connected to a main body (not shown) of the ultrasonic diagnostic equipment disposed at a backing material 209 side.
When the ultrasonic probe having the above configuration is used, first an audio lens 205 is contacted to a diagnosis object. Then, an electrical signal is applied to the piezoelectric transducer 201 through the FPCs 211, thereby an ultrasonic wave is generated from the piezoelectric transducer 201. The generated ultrasonic wave is sent to the diagnosis object through the audio lens 205, and reflected within the diagnosis object, and then received by the piezoelectric transducer 201. The received ultrasonic wave is converted to an electric signal in the piezoelectric transducer 201, and transferred to the main body of the ultrasonic diagnostic equipment through the FPCs 211.
In such configured ultrasonic probe, the FPCs 211 are bent at approximately 90 degrees in the vicinity of the jointed portion with the piezoelectric transducer 201. According to the finite deflection theory, bending stress exerted on the curved portions of the FPCs 211 exceeds 100 N/mm2, therefore the jointed portions of the FPCs 211 with the piezoelectric transducer 201 were easily broken due to the bending stress exerted on the curved portions of the FPCs 211. Particularly, in dicing, large machining stress is applied to the jointed portions of the FPCs 211 with the piezoelectric transducer 201, therefore the jointed portions were still further easily broken.
Thus, a configuration in which the FPCs are connected to the piezoelectric transducer without being curved by projecting an end portion of the piezoelectric transducer from an end face of the backing material has been developed. In the ultrasonic probe, the FPCs are arranged along the end face of the backing material, and the end portions of the FPCs are jointed with the earth electrode formed on a bottom of the projected end of the piezoelectric transducer.
However, when the end portion of the piezoelectric transducer is projected from the end face of the backing material, there is a problem that a structure having the projected portion floating in the air is formed, and thus the crack is easily occurred in the piezoelectric material due to the machining stress generated in the dicing. Since the crack in the piezoelectric material has a great influence to the ultrasonic characteristics, in recent years, dicing without damaging the piezoelectric material has been required.